Libya's Supreme Court ruled Thursday that the country's internationally recognized parliament is invalid, adding to an already tumultuous political scene in the deeply fractured North African state.

Islamist lawmakers questioned the House of Representative's constitutionality because the legislative body operates from the eastern city of Tobruk and not from the capital Tripoli or the second city, Benghazi.

The Tobruk-based parliament called an emergency meeting to review the court ruling.

Libya is in chaos as two rival governments and parliaments are struggling for control of the country's vast energy reserves three years after the overthrow of Moammar Gadhafi.

Western powers and Libya's neighbors fear the OPEC member nation is heading for a full-blown civil war, with former rebels who helped oust Gadhafi now using their guns to carve out their own fiefdom.

The parliament moved after an Islamist militia coalition seized the capital earlier this year. The Supreme Court remains in Tripoli, where a rival parliament is vying for power.

The decision came after gunmen stormed Libya's El Sharara oilfield on Tuesday and Wednesday, shutting down the country's biggest production facility in a blow to government efforts to keep the oil industry isolated from the spreading chaos.

It was not clear what happened exactly but rival tribes have fought over the area near the field twice in the past 12 months to press authorities to meet their financial and political demands.

Officials said on Thursday the gunmen had left the field. Oil company vehicles riddled with bullet holes could be seen on social media. A Libyan official said authorities hoped to restart production very soon but they needed resolve local conflicts first.

The closure will lower the OPEC member's oil production, last reported at around 800,000 bpd, by at least 200,000 bpd, worsening a budget crisis as oil revenues have been well below target due to repeated strikes across the country.

Thursday's court decision invalidates parliamentary elections held in June, which led to the formation of the current interim government.

Prime Minister Abdullah al-Thani's cabinet was sworn in by the Libyan parliament in September in Tobruk.

The Islamist coalition refuses to recognize al-Thani and supports its own government

That shadow government in Tripoli, which calls itself the Government of National Salvation, acknowledged the court's ruling in a statement in Arabic on its website but did not elaborate on the implications.